package top.kiterunner.learning.network_demo.time_cs_test;

import java.io.IOException;
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.SelectionKey;
import java.nio.channels.Selector;
import java.nio.channels.ServerSocketChannel;
import java.nio.channels.SocketChannel;
import java.util.Iterator;
import java.util.Set;

/**
 * AdorynZhao in Tencent-UESTC.
 * Source Code Created on 2017/8/8.
 */
public class MultiplexerTimeServer implements Runnable {

    private Selector selector;

    private ServerSocketChannel srvChannel;

    private volatile boolean stop;

    public MultiplexerTimeServer(int port) {

        try {
            selector = Selector.open();
            srvChannel = ServerSocketChannel.open();
            srvChannel.configureBlocking(false);
            srvChannel.socket().bind(new InetSocketAddress(port), 2014);
            srvChannel.register(selector, SelectionKey.OP_ACCEPT);
            System.out.println("The time server is start in port: " + port);
        } catch (IOException e) {
            e.printStackTrace();
            System.exit(1);
        }
    }

    public void stop() {
        this.stop = true;
    }

    @Override
    public void run() {
        while (!stop) {
            try {
                selector.select(1000);
                Set<SelectionKey> selectedKeys = selector.selectedKeys();
                Iterator<SelectionKey> iterator = selectedKeys.iterator();

                SelectionKey key = null;
                while (iterator.hasNext()) {
                    key = iterator.next();
                    iterator.remove();
                    try {
                        handleInput(key);
                    } catch (Exception e) {
                        key.cancel();
                        if (key.channel() != null)
                            key.channel().close();
                    }
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        }

        if (selector != null) {
            try {
                selector.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }


    private void handleInput(SelectionKey key) throws IOException {
        if (key.isValid()) {
            if (key.isAcceptable()) {
                ServerSocketChannel ssc = (ServerSocketChannel)key.channel();
                SocketChannel sc = ssc.accept();
                sc.configureBlocking(false);
                // Add the new connection to the selector
                sc.register(selector, SelectionKey.OP_READ);
            }

            if (key.isReadable()) {
                // Read the data
                SocketChannel sc = (SocketChannel)key.channel();
                ByteBuffer readBuf = ByteBuffer.allocate(1024);
                int readBytes = sc.read(readBuf);

                if (readBytes > 0) {
                    readBuf.flip();

                    byte[] bytes = new byte[readBuf.remaining()];

                    readBuf.get(bytes);

                    String body = new String(bytes, "UTF-8");
                    System.out.println("The time server receive order: " + body);

                    String currentTime = "QUERY TIME ORDER".equalsIgnoreCase(body) ? new java.util.Date(System.currentTimeMillis()).toString() : "BAD ORDER";
                    doWrite(sc, currentTime);
                } else if (readBytes < 0) {
                    // 对端链路关闭
                    key.cancel();
                    sc.close();;
                } else {
                    // 返回值为0，没有读取到字节，属于正常场景，忽略！
                    ;
                }
            }
        }
    }

    private void doWrite(SocketChannel channel, String response) throws IOException {
        if (response != null && response.trim().length() > 0) {
            byte[] bytes = response.getBytes();
            ByteBuffer writeBuffer = ByteBuffer.allocate(bytes.length);
            writeBuffer.put(bytes);
            writeBuffer.flip();
            channel.write(writeBuffer);
        }
    }
}
